The objective of this research is to study the regulation of coordinated gene activity in a eukaryote. To this end, the phenomenon of dosage compensation in Drosophila is being investigated since it represents a regulatory mechanism which deals with differences in the number (or doses) of X-linked genes normally occurring between males and females. The long-term goal of the proposed research is to understand a level of genetic organization which is not found among simpler prokaryotic organisms since it was evolved in higher multicellular forms to accommodate specific necessities of their reproductive biology and development.